JPS5677742A - Particle counting device - Google Patents

Abstract

PURPOSE:To prevent the miscounting due to the noise piled on the particle signal, by counting the particle detection signals when a coincidence is obtained between the particle detection signal higher than the threshold level and the fixed delay particle detection signal. CONSTITUTION:A control is given to the flow-in of the particle suspension to the particle detecting device 1 via the fluid control device 2, and a control is given to the detection circuit 4 which converts the particle signal from the device 1 into the electric pulse by the start-stop circuit 3 interlocking the device 2. The narrow-width pulse caused by the minute particle out of subject or the noise signal delivered by the circuit 4 and the wide-width particle detection pulse are supplied to the threshold level circuit 5. One of these two types of pulses receives directly a comparison with the threshold voltage from the reference voltage generating circuit 6 through the comparators 10 and 11. While the other pulse receives the same comparison via the delay circuit 9 having a delay of 5sec or less. Then the coincidence circuit 12 produces the coincidence output when a coincidence is obtained between the original signal delivered from the comparators 10 and 11 and the phase-shift signal. These coincidence outputs are counted by counter circuit 7. Thus the miscounting due to the noise or the like can be prevented. Furthermore, the noise approximate to the detection signal can also be eliminated if the monomulti is triggered by the comparator 11.